Silver halide photographic material containing a 2-propynylthio derivative as stabilizer

ABSTRACT

A process for stabilizing the sensitivity nuclei and the latent image nuclei in exposed silver halide emulsion layers of silver halide emulsions which are suitable for producing black and white images and which have been prepared in the usual manner and mainly contain latent image nuclei on the surface of the grain and which contain at least one 2-propynylithio derivative as stabilizer and a light-sensitive photographic material with at least one silver halide emulsion layer which material contains at least one 2-propynylthio derivative as stabilizer suitable for producing black-and-white images.

United States Patent von Ktinig et al. l l Oct. 7, 1975 {541 SILVER HALIDE PHOTOGRAPHIC 3.764.339 10/1973 Himmelmann et all 90/109 MATERIAL CONTAINING A 3.772.023 ll/l973 Nakajima et al 7. 96/109 Z-PROPYNYLTHIO DERIVATIVE AS STABILIZER Primary ExaminerW0n H. Louie, Jr. {75] Inventors: Anita von Kiinig; Helmut Reuss, Attorney, Agent, or Firm-Connolly and Hutz both of Leverkusen; Anneliese Miiller, Cologne, all of Germany [73] Assignee: Agfa-Gevaert Aktiengesellschaft, [57] ABSTRACT Leverkusen. Germany [22] Filed: Jan. 25 [974 A process for stabilizing the sensitivity nuclei and the latent image nuclei in exposed silver halide emulslon [2]] Appl No.: 436,478 layers of silver halide emulsions which are suitable for producing black and white images and which have been prepared in the usual manner and mainly contain [30] Foreign Apphcamm Pnomy Data latent image nuclei on the surface of the grain and Germany 2304322 which contain at least one Z-propynylithio derivative as stabilizer and a light-sensitive photographic mate- [52] 96/7? 96/109 rial with at least one silver halide emulsion layer which [5H "3 603C 1/34 003C 1/48 material contains at least one 2-propynylthio deriva- [58] Field Search 96/109 76 R tive as stabilizer suitable for producing black-andh't [56] References Cited w l 8 images UNITED STATES PATENTS 8 Claims, No Drawings 3.692,527 9/]972 von Konig l. 96/l09 SILVER I-IALIDE PHOTOGRAPHIC MATERIAL CONTAINING A 2-PROPYNYLTHIO DERIVATIVE AS STABILIZER This invention relates to a process for stabilizing photographic silver halide emulsions by adding suitable stabilizers which are particularly suitable for stabilizing the latent image nuclei in photographic silver halide emulsions.

When silver halide emulsions prepared by the usual processes are stored in the unexposed state, especially under tropical conditions, they suffer severe loss of sensitivity, flattening of the gradation and increased fogging. Not only the sensitivity nuclei but also the latent image nuclei of exposed silver halide emulsions are unstable in storage.

Degeneration of the latent image is generally apparent from the fact that an exposed material which has been stored before development is less sensitive than a material which was not stored after exposure. The reasons for the degeneration of the latent image are still not completely clear but it is thought that it is brought about by substances in the emulsion, e.g. impurities or additives, which oxidize part of the silver of which the latent image consists. Degeneration of the latent image is extremely troublesome in practice not only in films used for taking original photographs, which are usually stored for some time after exposure before they are developed, but also in copying materials if they are not developed immediately after exposure. Copying mate rials in the form of rolls in particular are often not developed until several days after exposure.

It is known that certain compounds added as stabilizers to photographic silver halide emulsions can also be used for stabilizing the latent image nuclei. Hydrazides are described for this purpose in British Pat. No. 1,073,546 and certain aminoalkylthioethers, e.gv aminoethylcystein, in Belgian Pat. No. 782,033.

However, the compounds mentioned in these Patents have disadvantages. Firstly, they do not achieve the above mentioned effect, namely that of stabilizing both the photographic layer and the latent image nuclei. or only to a slight extend. Secondly, they deleteriously affeet or even completely prevent hardening of gelatine with the usual hardeners.

It has now been found that both the latent image nuclei and the so-called sensitivity nuclei of silver halide emulsions which have been chemically ripened in the usual manner and which when exposed mainly form latent image nuclei on the surface of the silver halide grain can be rendered stable even under extreme conditions of storage such as storage under moist or tropical conditions by adding to the silver halide emulsions as stabilizers at least one Z-pyropynylthio derivative of the following formula:

in which R is alkyl containing up to 18 carbon atoms, aryl or a heteroeyelie group, e.g. an imidazole, oxazole, thiazole, triazole, tetrazole, oxadiazole, thiadiazole, benzimidazole, benzoxazole, benzothiazole, pyridine, pyrimidine, triazine, quinoline, quinazoline, purine or s-triazolo [4,3-al-quinoline ring;

R is hydrogen, sodium or potassium.

The above mentioned alkyl, aryl and heteroeyclie groups may be substituted, e.g. with alkyl, aryl, halogen, eyano, nitro, hydroxy, mercapto, amino, carboxyl, sulfo, sulfamoyl, propynylthio, alkylthio, or pyridyl groups, and these substituents may in turn be substituted, e.g. with those mentioned above.

The compounds given in the following Tables have proved to be particularly suitable:

Table 1 Compound R Melting or decomposition No. point l -C, H, oil 2 C ,H., oil 3 C, H oil 4 3 an Oil 5 C H oil 6 C,.,H=;. 26-27 7 -C ,.H 34

Table 2 Table 2 Cuminued Cumpuund No X R" Melting or decomposition point 18 S NH H30 19 U Q 77 Table 3 Table 4-Continued X RSCH C CH S-CH I CH Com- R' 3 pound Melting or decom- I L! No. position point 36 on so 82 (umpnund X R Melting or decom- No pnsiliun point I 26 S SO .-NH Cl 150 (decompj Table 4 3 5 1i Tr I (H N Com- R' pound Melting or dccom Nu. position point CL N 12: 1 3| CH COON:1 dccomp 210 32 CH;,CHCOOH 39 Q 33 (H -(OOH Ill-112 CH-COOH 34 oil 5 coon oil

Table 4-Continued Table 4-Continued Preparation of the compounds according to the invention is carried out by known methods, e.g. methods analogous to that described in German Pat. No. 946,143, by reacting the mercapto or thione derivatives with chloro or bromopropyne, preferably in an alkaline medium. Preparation of the compounds according to the invention will be explained with the aid of the following examples. The other compounds according to the invention may be obtained in analogous manner. In the infra-red spectrum, the compounds according to the invention all show the characteristic CH valency frequency at 3,300 cm which may be slightly shifted according to the substituents. and which may be less or more fully marked.

PREPARATION OF COMPOUND 7 A solution of 7.4 ml of 3-chloropropyne-( l in 40 ml of ethanol is added to a suspension of 28.6 g (0.1 mol) of octadecylmercaptan in a solution of 4 g of sodium hydroxide and L5 g of sodium iodide in 40 ml of water and 120 ml of ethanol. The suspension is left to stand at room temperature for 8 to 16 hours until a solid product starts to separate. After the suspension has been left to stand for l or 2 days at 4C, the crude product is extracted with ether and the ethereal solution is washed and dried and the ether is distilled off. Yield: 25 g, melting point: cm "C, infra-red band at 3300 cm.

PREPARATION OF COMPOUND 28 12.6 g (0.2 mol) of 2-mercapto-benzimidazole-6- sulfonic acid sodium are dissolved in 50 ml of l nsodium hydroxide solution with the addition of 50 ml of alcohol and 0.75 g of sodium iodide at 80C. After the addition ofa solution of 7.4 ml of 3-chloropropynel in 40 ml of ethanol, the reaction mixture is heated under reflux for 30 minutes and then acidified with hydrochloric acid after cooling. The precipitated oily product is purified by stirring it with ether. Yield: g, decomposition point: 305C; infra-red band at 3300 cm.

PREPARATION OF COMPOUND 27 A solution of 14.8 ml of 3-chloropropyne-( l) in 40 ml of methanol is added dropwise with stirring to a suspension of 30 g (0.2 mol) of 2-mercaptobenzimidazole in 20 ml of [0N sodium hydroxide solution and I60 ml of methanol at room temperature under an atmosphere of nitrogen. When the reaction mixture has been stirred for /2 hour, the suspension is concentrated by evaporation under vacuum. The residue is purified by recrystallization from chloroform. Yield: 24 g, melting point 160C, infra-red band at 3,300 cm".

PREPARATION OF COMPOUND 33 g (0.l mol) of thiomalic acid are dissolved in 60 ml of 5N soldium hydroxide solution with the addition of 50 ml of ethanol and 1.5 g of sodium iodide at 80C, and the reaction mixture is heated under reflux for 30 minutes after the addition ofa solution of 14.8 ml of 3- chloropropyne-( l in 30 ml of ethanol, and it is then acidified with hydrochloric acid after cooling. The product is extracted with ether. The ethereal solution is washed and dried and the ether is distilled off. The smeary residue is purified by redissolving and precipitating it in ether. Yield: 1 I ll l2C, infra-red band at 2270 cm.

PREPARATION OF COMPOUND 36 PREPARATION OF COMPOUND 43 A solution of 7.4 ml of 3-chloropropyne-( l in 15 ml of ethanol is added dropwise with stirring to a suspen- 12.3 g, melting point:

sion of 17.8 g (0.1 mol) of 3-mercapto-l-phenyl-l,2,4--

triazole in 20 ml of 5N sodium hydroxide solution and ml of ethanol, the temperature rising to about 28C. After 14 hours stirring at room temperature, the precipitated salt is filtered off and the filtrate is concentrated by evaporation under vacuum. The crude product is purified by redissolving it several times from ether. Yield: 14 g, melting point: 66 67C, infra-red band at 3300 cm.

The compounds according to the invention are eminently suitable both for increasing the stability of the latent image and acting as antifogging agents in lightsensitive black-and-white photographic materials. The substances according to the invention achieve stability of the latent image and reduction in the fog to a very high degree while yet preserving all the usual photographic properties. These depend of course to a large extend on the nature of the silver halide emulsion. Stabilization is provided even under conditions of prolonged storage of the material at mormal temperature or at elevated temperature is a heating cupboard or even under tropical conditions, i.e., at high moisture levels.

The Z-propynylthio derivatives according to the invention may be added to the photographic emulsion or auxiliary layers at any stage. They are preferably added in the form of solutions to the light-sensitive silver halide emulsion layer after chemical ripening or to the finished casting solution. Suitable solvents are water, aqueous alkalies, lower aliphatic alcohols, tetrahydrofuran, acetone, dimethyl formamide or mixtures thereof. The concentration of 2-propynylthio derivatives in the layers may vary within wide limits. It depends on the effect desired, the nature of the reproduction process or the composition of the photographic material.

In a photographic layer, in particular in a silver halide emulsion layer, quantities of 0.1 to about 10 g per mol of silver halide have generally been found suitable. The concentrations used are preferably between I and 5 g of the compounds according to the invention per mol of silver halide.

The compounds according to the invention may be used for stabilizing the latent image nuclei in the usual light-sensitive materials used for producing black-andwhite images, e.g. black-and-white original films or copying materials or reversal materials.

The usual silver halide emulsions are suitable for this invention. They may contain silver halide in the form of silver chloride, silver bromide or mixtures thereof, if desired with a small silver iodide content of up to l mols percent. In the case of copying materials, silver bromide emulsions are preferred, if desired with a silver iodide content of up to 10 mols percent.

The binder used for the photographic layers is preferably gelatine although this may be partly or completely replaced by other natural or synthetic binders. Suitable natural binders are e.g. alginic acid and its derivatives such as salts, esters or amides, cellulose derivatives such as carboxymethylcellulose, alkyl cellulose such as hydroxy ethyl cellulose, starch or derivatives thereof such as ethers or esters or carrageenates. The synthetic binders used may be polyvinyl alcohol, partly saponified polyvinyl acetate, and polyvinylpyrrolidone.

The emulsions may also be chemically sensitised, e.g. by adding sulfur compounds such as allylisothiocyanate, allylthiourea, and sodium thiosulfate at the stage of chemical ripening. Reducing agents may also be used as chemical sensitizers, e.g. the tin compound described in Belgian Pat. Nos. 493,464 or 568,687, or polyamines such diethylene triamine or aminomethylsulfinic acid derivatives, e.g. according to Belgian Pat. No. 547,323.

Noble metals such as gold, platinum, palladium, iridium, ruthenium or rhodium and compounds of these metals are also suitable chemical sensitizers. This method of chemical sensitization has been described in the article by R. KOSLOWSKY, Z.Wiss.Phot. 46, 65 72 l95l The emulsions may also be sensitized with polyalkylene oxide derivatives, e.g. with polyethylene oxide having a molecular weight of between 1,000 and 20,000 or with condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl substituted phenols, aliphatic earboxylic acids, aliphatic amines, aliphatic diamines and amides.

The condensation products have a molecular weight of at least 700, preferably above 1,000. These sensitizers may, of course, also be combined to achieve special effects as described in Belgian Pat. No. 537,278 and in British Pat. No. 727,982.

The emulsions may also be optically sensitized, eg with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, and oxonoles. Sensitizers of this kind have been described in the work by F. M. HAMER The Cyanine Dyes and related Compounds" I964 The emulsions may also contain other stabilizers in combination with those according to the invention, e.g. they may contain homopolar or salt-type compounds of mercury which contain aromatic or heterocyclic rings, such as mercaptotriazoles, simple mercury salts, sulfo nium mercury double salts and other mercury compounds, Azaindenes are also suitable stabilizers, especially tetraor pentaazaindenes and particularly those which are substituted with hydroxyl or amino groups. Compounds of this kind have been described in the article by BIRR, Z.Wiss. Phot. 47,2 58 (1952). Other suitable stabilizers are inter alia heterocyclic mercapto compounds e.g. phenylmercaptotetrazole, quaternary benzothiazole derivatives, benzotriazole, benzotriazole derivatives and mercapto substituted pyrimidine derivatives and the like, eg as described in British Pat. No.

990,06l and in US. Pat. No. 3,692,527. In particular, 2-mercapto-4-keto-3,4-dihydropyrimidine derivatives mentioned in the aforesaid US. Pat. No. 3,692,527 which contain at least one carboxyl or sulfonic group may be used in combination with the stabilizers according to the invention.

The emulsions may be hardened in the usual manner, for example with formaldehyde or halogenated aldehydes which contain a carboxyl group such as mucobromic acid, diketones, methan sulphonic acid esters, and dialdehydes.

EXAMPLE I A silver bormide emulsion containing l4 mols of silver chloride and l mol percent of silver iodide is prepared in the usual manner, washed and ripened to its optimum sensitivity by means of sulfur sensitizers. The ratio of gelatine to silver in the finished emulsion is 3.6:1, the pH 5.7.

The emulsion is sensitized with 10 ml per kg of emulsion of a 0.] percent aqueous solution of the optical sensitizer of the following formula:

The sensitized emulsion is then divided into four parts and the stabilizers shown in Table 5 below are added in the given quantities to the individual samples. Samples l and 2 contain known stabilizers. The stabilizer in Sample 2 has been described in US. Pat. No. 3,692,527. Sample 3 contains compound 42 as stabilizer according to the invention and Sample 4 contains a combination of the known stabilizer used in Sample 2 and compound l5 according to the invention.

Before the emulsions are cast on a layer support of baryta paper, 20 ml of 5 percent aqueous solution of saponin and 0.75 ml of a 30 percent aqueous solution of formaldehyde per kg of emulsion are added to each sample. The application of silver is 2.2 g AgNo /m The emulsion layer is covered with a protective layer of the following composition:

20 g of gelatine l litre of water 2.4 ml of 30 percent aqueous formaldehyde solution 7.5 ml of 5 percent aqueous saponin solution.

The samples which have been stored for 3 months are cut up into several strips and exposed behind a grey wedge and then developed for seconds at 20C in a developer of the following composition, either immediately or after 3 days storage at 22C and 65 percent relative humidity:

p-methylaminophenol sulfate sodium sulfite anhydrous hydroquinone sodium carbonate anhydrous potassium bromide made up with water to 1 litre.

The step with a density of 0.5 above the fog was determined in the resulting sensitometer strips. The number of steps obtained in the sensitometer strips which were processed immediately after exposure was compared with the number of steps in the strips which were stored for 3 days at 22C and 65 percent relative humidity. The differences in the number of steps, which may be positive or negative, were converted into relative exposure times, taking the relative exposure time of the sensitometer to strips which were immediately processed as equal to 100.

Table 6 shows that the compounds according to the invention are also highly efficient as antifogging agents.

We claim:

1. A light-sensitive photographic material for producing black and white images, comprising at least one silver halide emulsion layer and a stabilizer compound in an effective amount for stabilizing latent image nuclei "\"I3-1Z-Mercaplo-l-Hlihydrt1-4-keto-quinnzolinyl)l-hutyrie acid On comparing the samples, it is seen that the known stabilizers are ineffective or only slight effective as stabilizers for latent image nuclei. As shown by Samples 3 and 4, the compounds according to the invention produce very satisfactory stability of the latent image.

instead of compound 15 in Sample 4, compounds Nos. l8. l9, 20, 2l, 22, 23, 25, 28, 43 and 44 may be used in equal quantities, and instead of compound 42 in Sample 3, compound 34 may be used in equal quantities. These compounds give equally good results.

EXAMPLE 2 A washed silver bromide gelatine emulsion containing 0.l6 mol of silver bromide per litre was cast on a layer support of baryta paper in known manner after the addition of 20 ml of a percent aqueous saponin solution and 2 ml of a 30 percent aqueous formaldehyde solution and dried. The application of silver is l .5 to [.6 g/m".

The above mentioned emulsion was divided into several parts before it was cast. The stabilizers according to the invention were added to these parts in the form of a l percent solution in dimethylformamide. The quantities added are shown in Table 6 below.

The samples were developed fresh and after 48 hours storage in a heating cupboard at 60C and 40 percent relative humidity, using the developer mentioned in Example l for 2, 4 or 6 minutes at a developer temperature of 30C. The grey fog of the various materials was measured with a densitometer and the following results were obtained:

Table 7 Con Comcen- Density of fog pound No. tration Fresh sample Sample stored in mg/l development time heating cupboard 2 4 h min. Development time 2 4 6 min.

Control sample 0 0.08 0. l 3 0.19 0. I Z 0.17 0.27 17 I00 0.08 0.09 0.ll 0.l0 (H 024 l8 20 0.07 0.09 0. l 0. l0 0. l5 0.2.1 23 50 0.07 0.09 0.l l 0.ll 0. lo 0.24 27 50 0.08 0.09 0 09 0. Ill 0. l4 0.22 28 500 0.07 0.09 0.10 0.l0 0 12 (H3 40 50 006 (I08 012 0. l0 0.16 0.24 42 N10 0.07 0.07 0.09 0.09 0.13 0. I) 43 50 0,06 0.08 U, l 7 0. l0 0.13 0 I8 48 100 0,06 0.08 0, l 7 0.0) 0. l0 0 I7 occurring on the surface of the grain after imagewise exposure of the said silver halide emulsion layer wherein the improvement comprises the stabilizer compound is a 2-propynylthio derivative of the formula wherein R represents alkyl of from l-l8 carbon atoms, aryl group or a heterocyclic group selected from the group consisting of imidazole, oxazole, thiazole, triazole, tetrazole, oxadiazole, thiadiazole, benzimidazole, benzoxazole, benzothiazole, pyridine, pyrimidine, triazine, quinoline, quinazoline, purine or a 3-triazolo [4,3-a] quinoline;

R represents hydrogen. sodium or potassium.

2. A light-sensitive material according to claim 1 wherein R represents a l,3,4-thiadiazole, a 1,2,4- triazole, a benzothiazole, a benzimidazole or a carboxyphenyl group.

3. A light-sensitive material according to claim 1 which contains at least one additional stabilizer.

4. A lightsensitive material according to claim 3, wherein the additional stabilizer is a mercapto substituted pyrimidine.

5. A light-sensitive material according to claim i wherein R represents an alkyl or an aryl group substituted with a substituent selected from the group consisting of alkyl, aryl, halogen, cyano, nitro. hydroxy, mercapto, amino, carboxyl, sulfo sulfamoyl, propinylthio and pyridyl groups.

6. A light-sensitive material according to claim I wherein R represents a phenyl group.

7. A light-sensitive material according to claim 6 wherein R represents a phenyl group substituted with hydroxy or carboxy.

8. A light-sensitive material according to claim 4, wherein the mercapto-substituted pyrimidine is a 2-mercapto-4-keto-3,4-dihydro pyrimidine derivative of the formula dine, tetrahydropyridine, pyrimidine, pyrrole furan, thiophene, oxazole, isooxazole. imidazole or pyrazole ring; R or Z contains at least one carboxyl or sulfo group.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3),9l0a79%975 Ct. DATED von Konig et a1 INVENTOR(S) I It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below,

Front page, line 7 of the Abstract, "2-propynylithio" should read 2-propynylthio Column 2, line ll, "2-pyropynylthio" should read 2-propynylthio Column 5, compound 50 of Table 4, the formula should read as follows:

HCEC-CH -S-K If Column 6, in compounds 57 and 59 of Table 5, the phenyl group should be located under R Column 6, compound 58 of Table 5, the right hand of substituent X should read as follows: -CH -SCH -S-CH Column 7 line 28, "cm C" should read as 34C Column 7, line 29, "3300 m should read as 3300 cm Column 10, line 32, "Table 5" should read as Table 6 Column ll, line 45, "Table 6" should read as Table 7 Column 12, line 1, "Table 6" should read as Table 7 Column 12, the formula of claim 8 should read:

Signed and Emalccl this thirtieth D f March 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (omnu'ssimwr oj'Parems and Trademarks 

1. A LIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL FOR PRODUCING BLACK AND WHITE IMAGES, COMPRISING AT LEAST ONE SILVER HALIDE EMULSION LAYER AND A STABILIZER COMPOUND IN AN EFFECTIVE AMOUNT FOR STABILIZING LATENT IMAGE NUCLEI OCCURING ON THE SURFACE OF THE GRAIN AFTER IMAGEWISE EXPOSURE OF THE SAID SILVER HALIDE EMULSION LAYER WHEREIN THE IMPROVEMENT COMPRISES THE STABLIZER COMPOUND IS A 2-PROPYNYLTHIO DERIVATIVE OF THE FORMULA
 2. A light-sensitive material according to claim 1 wherein R1 represents a 1,3,4-thiadiazole, a 1,2,4-triazole, a benzothiazole, a benzimidazole or a carboxyphenyl group.
 3. A light-sensitive material according to claim 1 which contains at least one additional stabilizer.
 4. A light-sensitive material according to claim 3, wherein the additional stabilizer is a mercapto substituted pyrimidine.
 5. A light-sensitive material according to claim 1 wherein R1 represents an alkyl oR an aryl group substituted with a substituent selected from the group consisting of alkyl, aryl, halogen, cyano, nitro, hydroxy, mercapto, amino, carboxyl, sulfo sulfamoyl, propinylthio and pyridyl groups.
 6. A light-sensitive material according to claim 1 wherein R1 represents a phenyl group.
 7. A light-sensitive material according to claim 6 wherein R1 represents a phenyl group substituted with hydroxy or carboxy.
 8. A light-sensitive material according to claim 4, wherein the mercapto-substituted pyrimidine is a 2-mercapto-4-keto-3,4-dihydro pyrimidine derivative of the formula 